Friction drive type rubber crawlers have been proposed wherein an outer peripheral surface of a drive wheel contacts an inner peripheral surface of the rubber crawler, with drive force transmitted by friction. With rubber crawlers of this type, guide projections are provided to the inner peripheral face of an endless form crawler main body in order to guide for example the drive wheel and rollers. Lugs are formed on the outer peripheral face of the crawler main body (see Japanese Patent Application Laid-Open (JP-A) No. 2004-196189).
In such rubber crawlers, the thickness of the guide projections in the rubber crawler thickness direction is usually thicker than the thickness of the lugs. Accordingly, in cases in which the guide projections, the crawler main body, and the lugs are integrally vulcanize molded together, the points of slowest vulcanization (the points at which the smallest amount of cumulative heat is received from the mold) are deep portions within the guide projections. There is accordingly a need to continue vulcanization until the points of slowest vulcanization reach a specific degree of vulcanization in order to achieve specific rubber properties in the rubber crawler. Since increasing the vulcanization time raises manufacturing costs, a reduction in the vulcanization time is desired.
A reduction in the vulcanization time can be achieved by reducing the height of the guide projections, however it is necessary to secure a certain degree of height for the guide projections in order for the guide projections to be contacted by the drive wheel and the rollers in the crawler width direction, so as to guide the drive wheel and the rollers. It is moreover difficult to simply reduce the size of the guide projections from the perspective of durability.